U.S. patent application number 10/555619 was filed with the patent office on 2006-11-09 for sealable, multilayer, coextruded packaging film, its use and process for its production.
This patent application is currently assigned to TICONA GmbH. Invention is credited to Stammatis Ginossatis, Wolfram Goerlitz.
Application Number | 20060251876 10/555619 |
Document ID | / |
Family ID | 33427042 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060251876 |
Kind Code |
A1 |
Goerlitz; Wolfram ; et
al. |
November 9, 2006 |
Sealable, multilayer, coextruded packaging film, its use and
process for its production
Abstract
The invention relates to a sealable, multilayer, coextruded
packaging film with high transparency and high tensile strength.
The film is composed of at least one core layer A made from a
polyolefin with high tensile strength together with low elongation,
and of outer layers B and C arranged on the two sides. The core
layer A comprises from 50 to 100 % by weight of cyclic olefin
polymer (COC) having a T.sub.g of at least 60 .degree. C. The outer
layers B and C may comprise at least one sealable polymer and one
functional polymer. Intermediate layers may be arranged between
layer A and layers B and C improving adhesion between layers. This
film has a total thickness in the range from 20 to 200 .mu.m, the
core layer A making up from 5 to 60% of the total thickness of the
film. The film is used in "flow-pack" packages produced on
form-fill seal machines, or as a cover film on thermoformed blister
packages or on cups (lidding).
Inventors: |
Goerlitz; Wolfram;
(Wiesbaden, DE) ; Ginossatis; Stammatis;
(Koropi-Attiki, GR) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
TICONA GmbH
Professor-Staudinger-Strasse
Kelsterbach
DE
|
Family ID: |
33427042 |
Appl. No.: |
10/555619 |
Filed: |
May 4, 2004 |
PCT Filed: |
May 4, 2004 |
PCT NO: |
PCT/EP04/04694 |
371 Date: |
February 20, 2006 |
Current U.S.
Class: |
428/220 ;
206/531; 264/173.19; 428/354; 428/447; 428/476.3; 428/483;
428/523 |
Current CPC
Class: |
B32B 27/32 20130101;
B32B 7/12 20130101; Y10T 428/3175 20150401; B32B 2307/54 20130101;
Y10T 428/2848 20150115; Y10T 428/31938 20150401; B32B 27/08
20130101; Y10T 428/31797 20150401; Y10T 428/31663 20150401; B32B
2307/412 20130101; B32B 2553/00 20130101 |
Class at
Publication: |
428/220 ;
428/523; 428/354; 428/483; 428/476.3; 428/447; 206/531;
264/173.19 |
International
Class: |
B32B 27/36 20060101
B32B027/36; B32B 27/32 20060101 B32B027/32; B65D 83/04 20060101
B65D083/04; B32B 27/08 20060101 B32B027/08 |
Foreign Application Data
Date |
Code |
Application Number |
May 7, 2003 |
EP |
03010233.9 |
Claims
1. A multilayer packaging film comprising a core layer A comprising
an amount of from 50 to 100% by weight, based on the total weight
of the core layer A, of an amorphous cycloolefin copolymer (COC)
which has a glass transition temperature T.sub.g of at least
60.degree. C., and comprising at least two outer layers B and C on
the two sides of the core layer A, one of which comprises at least
one sealable polymer, and one of which comprises at least one
functional polymer, where between the core layer A and the outer
layers B and C may be arranged additional intermediate layers
bringing about firm bonding between the core layer A and the outer
layers B and C, and where the film has a total thickness in the
range from 10 to 200 .mu.m, wherein the core layer A makes up from
5 to 60% of the total thickness of the film.
2. The packaging film as claimed in claim 1, wherein the COC is a
copolymer of ethylene and/or of an .alpha.-olefin with a cyclic,
bicyclic, or multicyclic olefin.
3. The packaging film as claimed in 1, wherein the COC is a
copolymer made from ethylene and norbornene.
4. The packaging film as claimed in claim 1, wherein the functional
polymers comprise polymers further improving the barrier properties
of COC in terms of gas transmission rate or polymers which comprise
additives improving the frictional properties of the film.
5. The packaging film as claimed in claim 1, wherein the functional
polymers comprise polyamides, produced from the reaction of
diamines with dicarboxylic acids or by ring-opening of lactams, or
other polymers with functional properties.
6. The packaging film as claimed in claim 1, wherein the additives
comprise anti-blocking agents, or from oxides, or from
silicates.
7. The packaging film as claimed in claim 1, wherein the functional
polymers further comprise organic lubricants.
8. The packaging film as claimed in wherein the sealable polymers
comprise polyolefins and vinylacetate or sealable ionomeres.
9. The packaging film as claimed in claim 1, wherein the
intermediate layers comprise adhesion promoters, primer
compositions or adhesives.
10. The packaging film as claimed in claim 1, wherein its tensile
elongation modulus is in the range of at least 500 N/mm.sup.2.
11. The packaging film as claimed in claim 1, wherein its moisture
vapor transition rate normalised to 1 mm thickness is in the range
of less than 0.5 gmm/(m.sup.2day).
12. A process for producing a sealable, multilayer packaging film
as claimed in claim 1 wherein the polymer mixtures and polymers
forming the layers of the film are melted in separate extruders and
the melted polymers are coextruded through a flat-film die or a
tubular die and the resultant coextruded film is drawn off on one
or more rolls, whereupon it cools and solidifies, followed,
optionally by surface treatment of the film, thereby omitting any
stretching step.
13. The process as claimed in claim 12, wherein additives used are
present in the polymer or polymer mixture as it stands, or are
added via masterbatch technology.
14. (canceled)
15. (canceled)
16. The packaging film as claimed in 1, wherein the film has a
total thickness in the range from 20 to 150 .mu.m and the core
layer A makes up from 10 to 50% of the total thickness of the
film.
17. The packaging film as claimed in 1, wherein the core layer A
makes up from 15 to 40% of the total thickness of the film and
wherein the films tensile elongation modulus is in the range of at
least 700 N/mm.sup.2 and wherein the films moisture vapor
transition rate normalized to 1 mm thickness is in the range of
less than 0.35 g-mm/(m.sup.2day).
18. The packaging film as claimed in claim 1, wherein the
functional polymers comprise polyamides, produced from the reaction
of diamines with dicarboxylic acids or polyhexamethylenesebacamide
and poly-epsilon-caprolactam, or ethylene vinyl alcohol copolymers
or polyvinyl alcohols with varying degrees of hydrolysis and
polyethylene terephtalate or polybutylene terephthalate.
19. The packaging film as claimed in claim 1, wherein the additives
comprise anti-blocking agents which are inorganic particles made
from alkaline earth metal carbonates or from alkali metal
carbonates, or from oxides, or from silicates.
20. The packaging film as claimed in claim 1, wherein the
functional polymers further comprise polydialkylsiloxanes.
21. Flow-pack packages produced on form-fill-seal machines which
comprises the packaging film as claimed in claim 1.
22. A cover film on thermoformed blister packages or on cups
(lidding) which comprises the packaging film as claimed in claim 1.
Description
[0001] The invention relates to a sealable, multilayer, coextruded
packaging film having low elongation under mechanical load combined
with high transparency, suitable for application in "flow-pack"
packages produced on form-fill-seal machines, or as a cover film on
thermoformed blister packages or on cups (lidding).
[0002] The film of this invention comprises at least three layers,
between each of which additional primer layers can be arranged if
needed, in particular a core layer A comprising a polyolefin,
having high modulus or low elongation under load, and outer layers
B and C arranged on the two sides of the core layer A, these being
identical or different and composed of sealable polyolefins
(polyethylene, polypropylene) or of polymers having functional
properties. The film of the invention has exceptionally good
mechanical properties, i.e. low elongation under mechanical load.
The invention also relates to a cost-effective process for
producing said film, and to its use as a carrier for high-quality
print, and to the production of flow-pack packages on
form-fill-seal machines.
[0003] Films used for foodstuffs packaging must have special
properties in relation to their processability on packaging
machines, their printability, and their barrier properties with
respect to atmospheric gases such as oxygen, and with respect to
water vapor. For reasons of good multicolor printability and
processability on packaging machines, the need is for films
with-high modulus, low coefficient friction, and good
sealability.
[0004] This combination of features is usually not achievable using
a single homopolymer or polymer blends, since no single polymer
material possessing all these properties is available. The prior
art proposes various multilayer film structures to solve said
problem, in particular stretch-oriented films or laminates of
stretch-oriented films with unoriented sealant films.
[0005] Good-quality multicolor printability requires low elongation
in the printing press and little dimensional change in the film. In
addition, residual solvent content in the printing ink needs to be
low for food packaging applications. It is therefore desirable to
use elevated temperatures for efficient drying of the ink. The
specific manufacturing process for biaxially oriented films
typically gives them the required high modulus, i.e. low elongation
under load, and good dimensional stability at elevated
temperatures, and these films are widely used as carriers for
high-quality multicolor print. However, these films cannot in
themselves provide the required sealing properties needed for
conversion into packaging on industrial form-fill-seal machines.
Laminates of this printed film with a second, non-oriented film are
therefore typically used, where the second film contributes
additional functional properties as needed, i.e. superior sealing
properties or an additional barrier to moisture and gases.
[0006] The prior art films have a number of disadvantages.
Production of laminated films as described above involves an
undesirable multistep film production process with orientation and
subsequent lamination to a second film. These laminated asymmetric
film structures can curl, causing additional problems when packages
are made from precut panels.
[0007] It is therefore desirable to provide a film which is
suitable for high-quality multicolor printing and processing on
high-speed packaging machines, and which can advantageously be
manufactured in a one-step process by multilayer coextrusion
without any need for orientation or lamination to a second film.
While coextruded multilayer films are prior art and are widely used
for less demanding applications, they have disadvantages for the
intended application, due to lack of mechanical strength, and
mostly have disadvantageous tear properties, due to high elongation
of these films combined with low mechanical strength.
[0008] It is therefore an object of the present invention to
provide a novel multilayer packaging film with high suitability for
use on form-fill-seal machines to produce flow-pack packages or
lidding with high-quality multicolor printing. This object has been
achieved by producing a film in a conventional multilayer
coextrusion process, and incorporating an amorphous cycloolefin
copolymer (COC) into the multilayer film structure.
[0009] The invention therefore provides a multilayer film
comprising a core layer A comprising an amount of from 50 to 100%
by weight, based on the total weight of the core layer A, of an
amorphous cycloolefin copolymer (COC) which has a glass transition
temperature T.sub.g of at least 60.degree. C., and comprising at
least two outer layers B and C on the two sides of the core layer
A, one of which comprises at least one sealable polymer, and one of
which comprises at least one functional polymer, where between the
core layer A and the outer layers B and C may be arranged
additional intermediate layers bringing about firm bonding between
the core layer A and the outer layers B and C, and where the film
has a total thickness in the range from 10 to 200 .mu.m, preferably
from 20 to 150 .mu.m, wherein the core layer A makes up from 5 to
60% of the total thickness of the film, preferably from 10 to 50%,
particularly preferred from 15 to 40%.
[0010] The invention also provides a process for the production of
this film, and the use of the film for the production of flow-pack
packaging on form-fill-seal machines, or as a cover film on
thermoformed blister packs or on cups.
[0011] The cycloolefin copolymer (COC) used in the invention
preferably has a glass transition temperature T.sub.g of more than
60.degree. C., preferably from about 80 to 150.degree. C.
[0012] The cycloolefin copolymers (COC) used for the core layer A
of the multilayer film of the invention are generally composed of
ethylene units and/or of units comprising an alpha-olefin with a
cyclic, bicyclic or multicyclic olefin. Preferably, the COC is a
copolymer from ethylene and norbornene. Such COC are prepared in
the presence of transition metal polymerization catalysts described
in EP-A-0 407 870 or EP-A-0 485 893. The processes described there
are suitable to provide COC with low polydispersity
(M.sub.w/M.sub.n=2). This avoids disadvantages such as migration,
extractability or tack caused by the low-molecular-weight
constituents. The molecular weight of the COC is adjusted during
the preparation process by using hydrogen, careful catalyst
selection, and careful selection of the conditions of the
polymerization reaction.
[0013] Outer layers having functional properties in the sense of
the invention comprise polymers which further improve the good
barrier properties of COC in terms of the moisture vapor
transmission rate or polymers which comprise additives improving
the frictional properties of the film. Examples of these additives
are anti-blocking agents, such as inorganic particles made from
alkaline earth metal carbonates or from alkali metal carbonates, or
from oxides, or from silicates.
[0014] Other mineral additives are materials such as aluminum
oxide, aluminum sulfate, barium sulfate, calcium carbonate,
magnesium carbonate, silicates, such as aluminum silicate (kaolin),
and magnesium silicate (talc), silicon dioxide and titanium
dioxide.
[0015] Besides the inorganic additives, however, it is possible and
advantageous to use organic lubricants, such as
polydialkylsiloxanes of various composition.
[0016] According to the invention, the polymers used having
functional properties may comprise polyamides, produced from the
reaction of diamines with dicarboxylic acids or by ring-opening of
lactams. Examples of suitable polyamides are
polyhexamethylenesebacamide and poly-epsilon-caprolactam. Other
polymers with functional properties are polyvinyl alcohols with
varying degrees of hydrolysis, and polyesters, such as polybutylene
terephthalate.
[0017] According to the invention, suitable sealable layers are
layers made from polyolefins, in particular from PE, or from
copolymers of ethylene and propylene having a propylene content of
up to 10% by weight. Other suitable sealable polymers are ionomeres
such as .RTM.Surlyn 1705 from DuPont.
[0018] Besides the core layer A and the outer layers B and C, the
films of the invention may comprise other layers, if this is a
requirement for the technical application in the packaging of
certain packed goods. The additional layers here should, as far as
necessary, also have been bonded securely to the other layers of
the film, using adhesion promoter layers.
[0019] The combination of various polymers in a composite according
to the instant invention, whereby the composite being prepared by
the simple technique of coextrusion, combines the property profiles
of the different polymeric materials with one another in a
favorable manner. The layers of the film fit together to ensure
that the film composite has the mechanical properties needed,
specifically high tensile strength with low elongation, these being
required for high-quality multicolor printing and further
processing to give packaging, such as flow packs or lid films,
while also providing the water-vapor barrier and gas barrier needed
to preserve the contents, together with sealing properties.
However, in addition to an improvement in properties a reduction in
the cumulative thickness of the entire film structure is achieved,
giving either higher mechanical strength at a given film thickness
or a substantial rise in barrier action with respect to water
vapor, or, for given property profiles, a marked reduction in layer
thickness and, thus, a cost saving.
[0020] The film of the invention has a combination of the following
properties: [0021] High tensile elongation modulus measured
according to ASTM D822 (i.e. high tensile stresses with low
elongation); [0022] good barrier properties with respect to water
vapor according to DIN 53122 (i.e. low moisture vapor transmission
rate); [0023] good transparency and printability.
[0024] In terms of the instant invention, a high tensile elongation
modulus is understood to be in the range of at least 500
N/mm.sup.2, preferred at least 700 N/mm.sup.2, most preferred at
least 800 N/mm.sup.2.
[0025] In terms of the instant invention, good barrier properties
are understood to be in the range of below 0,5 gmm/(m.sup.2-day),
preferred below 0,35 gmm/(m.sup.2-day).
[0026] One or more outer layers of the multilayer film of the
invention may moreover also comprise neutralizing agents,
stabilizers, lubricants, hydrocarbon resins, and/or antistats, or
antifogging agents.
[0027] Stabilizers which may be used are the customary stabilizing
compounds for ethylene polymers, for propylene polymers, and for
other alpha-olefin polymers. The amount added of these is from 0.05
to 2.0% by weight. Particularly suitable materials are phenolic
stabilizers, alkali metal stearates, alkaline earth metal
stearates, and/or alkali metal carbonates, alkaline earth metal
carbonates. Preference is given to an amount of from 0.1 to 0.6% by
weight, preferably from 0.15 to 0.3% by weight, of phenolic
stabilizers whose molar mass is more than 500 g/mol. Particularly
advantageous materials are pentaerythritol
tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate or
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene.
[0028] Lubricants are higher aliphatic amides, higher aliphatic
esters, and waxes and metal soaps, and also polydimethylsiloxanes.
The effective amount of lubricant is in the range from 0.1 to 3.0%
by weight. A particularly suitable method is addition of higher
aliphatic amides in the range from 0.15 to 0.25% by weight in base
layers and/or outer layers.
[0029] Preferred antistats are alkali metal alkanesulfonates,
polyether-modified, i.e. ethoxylated and/or propoxylated,
polydiorganosiloxanes (polydialkylsiloxanes,
polyalkylphenylsiloxanes, and the like), and/or the substantially
straight-chain and saturated aliphatic, tertiary amines having an
aliphatic radical having from 10 to 20 carbon atoms, these having
substitutions with .alpha.-hydroxy-(C.sub.1-C.sub.4)-alkyl groups,
particularly suitable materials being
N,N-bis(2-hydroxyethyl)alkylamines having from 10 to 20 carbon
atoms, preferably from 12 to 18 carbon atoms, in the alkyl radical.
The effective amount of antistat is in the range from 0.05 to 3.0%
by weight. Glycerol monostearate is another preferred antistat.
[0030] Where appropriate, the covering also comprises organic
compounds having polar and non-polar groups. Preferred organic
compounds are alkanols and fatty acids having from 8 to 30 carbon
atoms in the alkyl group, in particular fatty acids and primary
n-alkanols having from 12 to 24 carbon atoms, and also
polydiorganosiloxanes and/or polyorganohydrosiloxanes, such as
polydimethyl-siloxane and polymethylhydrosiloxane.
[0031] Addition of sufficient amounts of these substances can also
permit production of a white or opaque embodiment of the film.
[0032] Semicrystalline polyolefins which may generally be used are
polymers of ethylene or .alpha.-olefins, such as propene, n-butene,
isobutene, and higher .alpha.-olefins, or copolymers of these. Use
may advantageously be made of polypropylene, polyethylenes such as
HDPE, LDPE and LLDPE, or else of mixtures prepared from these.
Preference is given to mixtures of LDPE and LLDPE in any mixing
ratio from 5 to 100%. Where appropriate, the semicrystalline
polyolefin comprises other additives, each in an effective
amount.
[0033] The invention also provides a process for producing the film
of the invention, in which all the polymers/polymer mixtures
forming the film are melted in separate extruders, and then the
melt(s) is/are coextruded through a flat-film or annular die,
formed to a film, cooled and solidified in a cast or blown film
process and, followed, where appropriate, only by surface treatment
of the film, thereby omitting the stretching steps usually needed
for high strength films.
[0034] The additives used where appropriate may be present in the
polymer or polymer mixture as it stands, or may be added via
masterbatch technology. The film is then wound up in the usual way,
using wind-up equipment.
[0035] The take-off roll or take-off rolls which also cool(s) and
solidify(ies) the extruded film are mostly maintained at a
temperature from 20 to 90.degree. C.
[0036] Where appropriate, one or both surfaces of the film may be
corona- or flame-treated by one of the known methods, the usual
result being an improvement in the surface polarity, and therefore
the printability, of the treated surface.
[0037] The test methods used in the examples listed below were as
follows: TABLE-US-00001 Tensile elongation modulus ASTM D882
Moisture Barrier properties 38.degree. C. at 90% DIN rel. humidity
53122
WORKING EXAMPLES
[0038] Coextrusion was used to produce a number of multilayer
films, using a flat-film die (example 1) in a cast film process, or
using an annular die in a blown film process (examples 2 to 7).
These films had total thickness of from 50 to 120 .mu.m and
comprised at least five layers, a base layer A and two outer layers
B1/B2 and C1/C2, bonded to the base layer by two tie layers (primer
layers). The thickness of each layer is shown in the table
below.
[0039] The base layer A comprised thermoplastic COC having an
amorphous structure based on ethylene and norbornene from Ticona
GmbH, Germany, (.RTM.Topas 8007 and .RTM.Topas 6015 with T.sub.g of
80.degree. C. and 160.degree. C., respectively). The base layer in
some of the samples also comprised a blend of COC with linear low
density polyethylene (LLDPE).
[0040] The films were printed on a 6-color gravure printing
machine.
[0041] These multilayer films were used to produce flow-pack
packages on horizontal form-fill-seal machines (type: ULMA PV 350,
Spain).
[0042] Films comprising laminated oriented outer layers B of
polyester or polyamide and sealant layers C of polyethylene were
used for comparison purposes as comparison examples 1 and 2.
[0043] The performance of all of the samples produced along with
the working examples in the printing and packaging processes was
comparable with or better than that of the films produced along
with the comparative examples. TABLE-US-00002 TABLE 1 Layer Total
Thickness Thickness Example Layer structure (.mu.m) (.mu.m) 1
Structure 1; layer 17/5/7/5/16 50 A = 7 .mu.m COC 2 Structure 2;
layer 20/5/5/10/25 65 A = 10 .mu.m COC/LLDPE blend (80:20) 3
Structure 2; layer 20/5/5/10/25 65 A = 10 .mu.m COC/LLDPE blend
(90:10) 4 Structure 2; layer 20/5/5/10/25 65 A = 10 .mu.m COC 5
Structure 3; layer 15/5/5/15/5/20 65 A = 15 .mu.m COC 6 Structure
3; layer 25/5/5/20/5/22 85 A = 20 .mu.m COC 7 Structure 3; layer
40/5/5/25/5/40 120 A = 25 .mu.m COC
[0044] TABLE-US-00003 TABLE 2 Structures Structure 1
PA/Tie/COC/Tie/Ionomer Where COC has T.sub.g of 160.degree. C.
(.RTM.Topas 6015, Ticona) PA is a PA6 (.RTM.Ultramid 35, BASF) Tie
is an MAA-grafted polyolefin (.RTM.Bynel 41E623, DuPont) Ionomer
(.RTM.Surlyn 1705, DuPont) Structure 2 PA/EVOH/Tie/COC/LLDPE Where
COC has T.sub.g of 80.degree. C. (Topas 8007, Ticona) PA is a PA6
(Ultramid 35, BASF) EVOH is a 38% copolymer (H171 from EVALco) Tie
is an MAA-grafted polyolefin (Bynel 41E623, DuPont) LLDPE has a
density of 0.910 g/cm.sup.2 (ExxonMobil 1012CA) Structure 3
PA/EVOH/Tie/COC/Ionomer Where COC has T.sub.g of 80.degree. C.
(Topas 8007, Ticona) PA is a PA6 (Ultramid 35, BASF) EVOH is a 38%
copolymer (H171 from EVALco) Tie is an MAA-grafted polyolefin
(Bynel 41E623, DuPont) Ionomer (Surlyn 1705, DuPont)
COMPARATIVE EXAMPLES
[0045] The following comparative films were laminated, comprising
an oriented film made from polyamide or polyester and a
non-oriented film made from polyethylene: TABLE-US-00004 TABLE 3
Comparative examples, laminates 92 .mu.m oPET/PE 12 .mu.m oPET/80
.mu.m PE 85 .mu.m oPA/PE 15 .mu.m oPA/70 .mu.m PE
[0046] oPET means oriented polyethyleneterephthalate,
[0047] oPA means oriented polyamide. TABLE-US-00005 Tensile ASTM
D882 elongation modulus: F1 force in N at 1% elongation of 15 mm
strip, setup according to ASTM D882, MVTR DIN 53122, at 38.degree.
C. and 90% rel. humidity. Results given as moisture vapor
transmission rate of sample film in units of g/(m.sup.2 day) and
for comparison purposes also calculated thickness independent
permeability coefficients for water vapor in units of g mm/(m.sup.2
day).
[0048] The results from the examples and from the comparative
examples are shown in Table 4 below: TABLE-US-00006 TABLE 4 Modulus
Modulus F1 F1 MVTR Property Machine Transverse Machine Transverse
MVTR Permeability Condition direction direction direction direction
Film coefficient Unit N/mm.sup.2 N/mm.sup.2 N N g/(m.sup.2 day) g
mm/(m.sup.2 day) Example 1 710 570 5.3 4.3 9.3 0.47 Example 2 841
856 8.6 8.8 5.7 0.37 Example 3 877 919 8.7 9.1 5.5 0.36 Example 4
1025 1016 10.5 10.4 5.3 0.34 Example 5 1150 1123 11.7 11.4 4.0 0.26
Example 6 1156 1181 14.7 15.0 3.1 0.26 Example 7 994 925 17.9 16.7
2.4 0.29 Comp. example 1 723 740 9.8 10.0 6.2 0.56 Comp. example 2
420 440 5.4 5.7 7.0 0.60
[0049] Mechanical properties at elevated temperatures were
evaluated by measuring storage modulus at temperature of 70.degree.
C. by DMA (dynamic mechanical analysis). Equipment: GABO Qualimeter
EPLEXOR 150 N. Conditions: static strain=0,7%, dynamic strain=0.3%.
Frequency: 10 Hz.
[0050] Results are shown in Table 5 below.
[0051] At a temperature of 70.degree. C. all films prepared
according to working examples of the instant invention had higher
storage modulus than the films prepared along with comparative
examples. TABLE-US-00007 TABLE 5 Storage Modulus Sample Temperature
N/mm.sup.2 Example 1 70.degree. C. 540 Example 4 70.degree. C. 600
Comp. Example 1 70.degree. C. 340
[0052] Film layer sequences of films according to the invention-are
not limited to those given in the above examples. Additional
examples of structures with 5 to 9 layers are exemplified in the
following table below:
[0053] No. Layer Sequence [0054] Example 8
PA/EVOH/tie/A(COC)/(tie)/sealant (PE, EVA.) [0055] Example 9
PBT/tie/EVOH/tie/A(COC)/sealant (PE-LLD) [0056] Example 10
PA/EVOH/tie/A(COC)/PE-LLD/tie/sealant (lonomer) [0057] Example 11
LDPE/tie/EVOH/tie/A(COC)/PE-LLD/A(COC)/tie/sealant (lonomer) [0058]
Example 12 TB/tie/EVOH/tie/A(COC)/PE-LLD/TB Wherein:
[0059] A(COC) denotes the core layer A containing at least 50% of
amorphous polyolefin. TB denotes additional layers comprising a
blend of COC and Polyethylene (less than 30% of COC)
[0060] Examples 8 to 10 stand for examples for different functional
outer layers (sealant and oxygen barrier);
[0061] Example 11 illustrates an example for a core layer split
into two sublayers;
[0062] Example 12 illustrates an example for a low curl film
containing additional outer layers comprising of a COC-blend.
* * * * *